Process for treating cellulose fibers and composition therefor



Patented Aug. 28, 1951 PROCESS FOR TREATING CELLULOSE FIBERS ANDCOMPOSITION THERE- FOR Thomas C. Whitner, Elizabeth, N. J.

No Drawing. Application July 18, 1947, Serial No. 761,987

I -Clainris.

This invention relates to the treating of cellulose fibers andparticularly to impregnating such fibers with sericeous material.

In U. S. Patent 2,417,388 I have disclosed a method for impregnatingcellulose fibers with .sericeous material and which involves dissolvingsilk fibers in an aqueous solution of an al- .kylolamine-copper complexand an alkali metal hydroxide; then saturating cellulose fibers withthis solution; and afterwards washing the saturated fibers with anaqueous solution of an acidic agent which forms water-soluble salts withthe copper complex and the alkali metal hydroxide. .Ihave describedanother method (in my copending application, Ser. No. 748,674) forimpregnating cellulose fibers which comprises dissolving .silk fibers inan aqueous soution containing a tetra-alky'lol ammonium hydroxide and acopper complex thereof, saturating the cellulose fibers with thissolution, and'afterwards washing the fibers with an aqueous solution ofan acidic agent. The latter, of course, should form water-soluble saltswith the copper complex, as wiell as with the tetra-alkylol ammoniumhydrox- 1 e.

My experiments involving impregnation of cellulose fibers with sericeousmaterial have indicated that silk fibers are insoluble, or substantiallyso, in an aqueous solution of an alkylolamine-copper complex as well asin an aqueous solution of a tetra-alkylol ammonium hydroxide. However,when these two substances (the copper complex and the tetra-alkylolammonium hydroxide) are present simultaneously in an aqueous solution,then the latter becomes a solvent for silk fibers. Moreover, the solventeffect for such fibers is enhanced or increased if a small proportion ofan alkali metal hydroxide, such as sodium or potassium hydroxide, isalso present in solution with the alkylolamine-copper complex and thetetra-alkylol ammonium hydroxide.

The aqueous solutions suitable for my purpose may be prepared in anyconvenient manner. For example, a water-soluble copper salt (such ascopper chloride, sulfate or acetate) is dissolved in water, and to thissolution is added slowly an .alkylolamine until the precipitate ofcopper hydroxide (which is .formed at first) redissolves thus givingrise to a clear blue aqueous solution of the alkylolamine-coppercomplex. In this solution then is dissolved a tetra-alkylol ammoniumhydroxide and, if desired, a small proportion of an alkali metalhydroxide. The resulting aqueous liquid afterwards is employed asasolvent for silk fibers. Another method involves precipitating copperhydroxide from an aqueous ,solution of a copper salt with the aid of analkali metal hydroxide, filtering the precipitate and washing it withwater until substantially free of all alkali and salts, dissolving thewashed copper hydroxide in an aqueous solution of an alkylolamine, andthen dissolving a tetra-alkylol ammonium hydroxide and silk fibers (inthe order named) in the aqueous solution of copper compleX.

After the aqueous solution of silk is prepared, the cellulose fibers canbe impregnated therewith in any convenient manner. To illustrate,cellulose fibers may be immersed in the solution of silk and workedtherein until they are completely saturated. Or, the solution of silkmay be dropped or sprayed onto the fibers until the latter aresaturated. Any other appropriate method can be employed, provided thecellulose fibers are thoroughly and completely impregnated thereby.

The next operation consists in washing the impregnated cellulose fiberswith an aqueous solution of an acidic agent, e. g., hydrochloric orsulfuric acid or sodium or potassium acid sulfate, whereby the coppercomplex is transformed into water-soluble salts (copper and alkylolaminesalts) and the tetra-alkylol ammonium hydroxide also is changed into awater-soluble salt. If an alkali metal hydroxide was present insolution, the acidic agent should furnish a water-soluble salt oninteraction with it. After washing with the aqueous solution of acidicagent, the cellulose fibers are rinsed thoroughly with water to removesubstantially all acidic agent and watersoluble salts which may havebeen retained by them. The fibers then are dried.

The following examples will illustrate my invention.

Example 1.Crystalline copper sulfate (CuSO4-5H2O) was dissolved in waterand to the aqueous solution was added triethanolamine slowly until theprecipitate of copper hydroxide (first formed) dissolved and a deep bluecolored solution was obtained. The latter was diluted with water untilits concentration was equivalent to 2 g. of copper salt per cc. ofsolution. Next, the solution was admixed with one-half its volume of anequeous solution of 40 per cent tetraethanol ammonium hydroxide. In theresulting liquid was dissolved silk until its concentrating was 1.3 percent.

A sample of bleached cotton cloth was immersed in some of the silksolution for 1 hour at 3 room temperature. The sample then was removed,Washed with dilute aqueous sulfuric acid and afterwards with water. Thefabric was dried by exposure to the atmosphere. This treated cloth had amuch smoother and even silky feel as compared with the untreatedmaterial.

This treated sample and also one of the original bleached cloth weredyed separately in the following manner: Each fabric was placed in abath consisting of 100 parts of water (per 1 part of cloth) and in whichwas dissolved an amount of a red substantive dye equal to 12 per cent ofthe weight of the fabric. After the samples had become saturated withthe dye solution, the temperature of each bath was increased to 60 C.over a period of minutes, maintained at 60 to 65 C. for 30 minutes, andthen each bath was allowed to cool to room temperature. The fabrics wereremoved from the baths, rinsed well with cold water, and air dried.

Both samples of dyed material were red in color, but the treated cottongoods was a darker shade of red thanthe untreated fabric.

Example 2.-Copper hydroxide was prepared by dissolving cupric chlorideand approximately one-third of its weight of ammonium chloride in water,adding sufiicient aqueous sodium hydroxide to effect substantiallycomplete precipitation of dissolved copper as the hydroxide, filteringthe precipitate and washing it with water until substantially free ofall alkali and salts, and then drying the precipitate by exposure to theatmosphere.

The dried material was admixed with water, and ethanolamine was addedslowly to the mixture until all of the water-insoluble copper compounddissolved and a clear blue solution was obtained. The latter was dilutedwith water until the concentration of copper therein was equivalent to6.4 g. of copperoxide (CuO) per 100 cc. of solution. The latter then wasadmixed with one-third its volume of per cent tetraeethanol ammoniumhydroxide. Small portions of silk cloth were added to this solution ofcopper complex slowly and with stirring until silk no. longer appearedto dissolve therein.

Bleached cotton yarn was immersed in some of the silk solution for 1hour at room temperature. The yarn then was removed, washed successivelywith aqueous sulfuric acid and with water, and afterwards was air dried.This treated sample had a smooth silky feel as compared with theuntreated bleached yarn.

Example 3.Crystalline copper sulfate (CuS04.5H2O) was dissolved inwater, triethanolamine added until a clear blue solution was obtained,and the latter then was diluted with water until its concentration wasequivalent to 13.3 g. of the copper salt per 100 cc. To this liquid wasadded one-third its volume of 40 per cent tetraethanol ammoniumhydroxide. In the resulting solution was dissolvedsuflicient potassiumhydroxide to react with the salt (formed by inter.- action of thealkylolamine and copper salt) and to give substantially 1 per cent ofthe free or uncombined alkali metal hydroxide. During dissolution of thelatter, some crystalline salt (apparently potassium sulfate)precipitated. This material was. separated by filtration and thefiltrate was saturated with dissolved silk fibers.

Unbleached cotton cloth was immersed for 2 hours at room temperature insome of the silk solution. Afterwards, the cloth was removed from theliquid and washed suocessivelywith dilute aqueous sulfuric acid and withWate and 4 then air dried. This treated cloth had a very smooth feel ascompared with the untreated fabric.

A portion of the treated cotton goods and also one of the untreatedmaterial were dyed in the following manner: Each sample was placed in adye bath consisting of parts of water per 1 part of cloth and containing5 per cent (on weight of cloth) of a red acid dye dissolved therein.Each sample was kept immersed in the respective bath for 3 hours at roomtemperature. Afterwards, the fabrics Were removed from the baths, rinsedwell with cold water, and air dried.

Both samples were a light red in color, but the silk-impregnated cottonwas a darker shade of red than the other untreated cotton.

Example 4.Copper hydroxide was prepared as indicated in Example 2. Thedry hydroxide was admixed with approximately 6 times its weight of waterand diethanolamine was added slowly to the mixture until a clear bluesolution was obtained. To this liquid was added one-half of its volumeof 40 per cent aqueous tetra-ethanol ammonium hydroxide and in theresulting solution was dissolved substantially 3 per cent of sodiumhydroxide. On standing for several hours a small quantity of precipitatesettled. This was removed by filtration and the clear solution onanalysis gave a copper content equivalent 'to.5.6 g. of copper oxide(CuO) per 100 cc. This clear liquid was saturated with dissolved silkfibers.

Unbleached cotton yarn was covered with some of this silk solution andworked therein for 1 hour at room temperature. Afterwards, the yarn waswashed successively with aqueous sulfuric acid and. water, and thendried; This treated yarn had a very silkyfeel and a distinct scroop ascompared with the untreated yarn.

It will be seen that my invention involves preparing an aqueous solutioncontaining an al kylolamine-copper complex and a tetra-alkylol. ammoniumhydroxide and dissolving silk fibers" therein. The solubility of silk insuch an aqueous solution can be increased by the prior dissolution of asmall proportion, say 0.5 to 4 per cent, of an alkali metal hydroxide,such as sodium or potassium hydroxide. My invention also includesimpregnating cellulose fibers with the aqueous solution of silk(prepared as just indicated) and afterwards washing the fibers with anaqueous solution of an acidic agent forming water-soluble salts and withthe copper complex and tetraalklyol ammonium hydroxide and also withalkali metal hydroxides, if the last-named substance be presented in thesilk solution. This step of washing with the aqueous solution of' acidicagent effects precipitation of sericeous material in and/or on thecellulose .fibers. Also, a considerable proportion of the water-solublesalts formed during the washing step are eliminated from the cellulosefibers. Next, the cellulose fibers are washed'well'with water to effectsubstantially complete removal from them of all acidic agent and allwater-soluble salts.

Aklylolamines which are suitable for my purpose may be eithermonalkylolamines,' such as ethanolamine or 2-amino-2-methyl-propanol, orpolyalkylolamines, such as diethanolamine, triethanolamine or2-amino-Z-methylpropanediol- 1,3. It will be noted that these compoundsalso are either monohydroxy or polyhydroxy substances. Tetra-alkylolammonium hydroxides which are applicable inpreparing the aqueoussolutions of silk can be exemplified by tetraethanol, tetra-propanol anditetra -butanol ammonium hydroxide.

In making the aqueous solutions intended as solvents for silk, I find itconvenient first to prepare the alkylolamine-copper complex dissolved.in the aqueous medium. As previously mentioned, this preparation may beeffected. by .dissolving a copper salt in 'water and then .adding analkylolamine slowly to the solution until the precipitate which isformed at first eventually dissolves. Or, copper hydroxide may beprecipitated from the solution of copper salt with the aid of an alkalimetal hydroxide (or other suitable alkali hydroxide), washed with wateruntil free of any substantial proportions of alkali and salts, and thendissolved in an aqueous solution of the aklylolamine. A slight excess ofthe alklyolomine over that required for changing the copper into thecopper complex apparently is not harmful. To the solution ofalklyolamine-copper complex then is added the tetraalkylol ammoniumhydroxide in whatever proportion may .be necessary or desirable.Afterwards, the alkali metal hydroxide (either as a solid or in aqueoussolution) is incorporated in the solution of alklyolamine-copper complexand substituted ammonium hydroxide. Of course, between any one of theabove-mentioned steps or following the last one, dilution with water togive a solution of desired concentration of ingredients is permissible.

The quantity of silk which can be dissolved in the solution of coppercomplex will depend upon the proportion of the complex, of thetetraalkylol ammonium hydroxide and of the alkali metal hydroxide. Byvarying these three factors it is possible to obtain solutions whoseconcentrations of silk will vary over a considerable range. Silk fibers,before dissolution in the copper solution, preferably are subjected to adegumming operation or treatment. If desired, they may be bleached also.

Cellulose fibers which are suitable for my purpose include cotton, linenand the like. Before being impregnated with the silk solution, suchfibers should be substantially free of extraneous materials such assizing and the like. Cellulose fibers which are unbleached, bleached,bleached and mercerized, or unbleached and mercerized can be treatedaccording to this invention. The so-called regenerated cellulose fibersare also applicable. Furthermore, the fibers may be in the form of loosefibers, yarn or cloth.

What I claim is:

1. The process for treating cellulose fibers which comprisesimpregnating saidfibers with an aqueous solution of essentially analkylolaminecopper complex and an amount of a tetra-alkylol ammoniumhydroxide to form with said complex a solvent for silk fibers and inwhich solution is dissolved silk, washing said impregnated fibers withan aqueous solution of an acidic agent yielding water-soluble salts withsaid copper complex and with said tetra-alkylol ammonium hydroxide, andremoving substantially all of said watersoluble salts from saidcellulose fibers.

2. The process for treating cellulose fibers which comprisesimpregnating said fibers with an aqueous solution of essentially analkylolaminecopper complex and an amount of tetra-ethanol I ammoniumhydroxide to form with said complex a solvent for silk fibers and inwhich solution is dissolved silk, washing said impregnated fibers withan aqueous solution of an acidic agent yielding water-soluble salts withsaid copper complex and with tetra-ethanol ammonium hydroxide, andremoving substantially all of said watersoluble salts from saidcellulose fibers.

. .-complex a solvent for silk fibers and in which solution is dissolvedsilk, washing said impregnated fibers with an aqueous solution of anacidic agent yielding water-soluble salts with said copper complex andwith tetra-ethanol ammonium hydroxide, and removing substantially all ofsaid watersoluble salts from said cellulose fibers.

4. The process for treating cellulose fibers according to claim 3 inwhich the monoalkylolamine-copper complex is ethanolamine-coppercomplex.

5. The process for treating cellulose fibers which comprisesimpregnating said fibers with an aqueous solution of essentially apolyalkylolamine-copper complex and an amount of tetraethanol ammoniumhydroxide to form with said complex a solvent for silk fibers and inwhich solution is dissolved silk, washing said impregnated fibers withan aqueous solution of an acidic agent yielding water-soluble salts withsaid copper complex and with tetra-ethanol ammonium hydroxide, andremoving substantially all of said water-soluble salts from saidcellulose fibers.

6. The process for treating cellulose fibers according to claim 5 inwhich the polyalkylolaminecopper complex is diethanolamine-coppercomplex.

7. The process for treating cellulose fibers according to claim 5 inwhich the polyalkylolaminecopper complex is triethanolamine-coppercomlex.

8. A bath for impregnating cellulose fibers which comprises an aqueoussolution of essentially an alkylolamine-copper complex and an amount ofa tetra-alkylol ammonium hydroxide to form with said complex a solventfor silk fibers, and silk dissolved therein.

9. A bath for impregnating cellulose fibers which comprises an aqueoussolution of essentially an alkylolamine-copper complex and an amount oftetra-ethanol ammonium hydroxide to form with said complex a solvent forsilk fibers, and silk dissolved therein.

10. A bath for impregnating cellulose fibers which comprises an aqueoussolution of essentially a monoalkylolamine-copper complex and an amountof tetra-ethanol ammonium hydroxide to form with said complex a solventfor silk fibers, and silk dissolved therein.

11. A bath for impregnating cellulose fibers which comprises an aqueoussolution of essentially a polyalkylolamine-copper complex and an amountof tetra-ethanol ammonium hydroxide to form with said complex a solventfor silk fibers, and silk dissolved therein.

12. The process as set forth in claim 1 in which the aqueous solutioncontains a concentration equivalent to 2 g. of copper salt per c. c. ofsolution and which aqueous solution is admixed with from A9, to itsvolume of an aqueous solution of 40 tetra-alkylol ammonium hydroxide.

13. The process of claim 12 in which the alkylol derivative istetra-ethanol ammonium hydroxide.

14. A bath as set forth in claim 8 in which the aqueous solutioncontains a concentration equivalent to 2 g. of copper salt per 100 c. c.of solution and which aqueous solution is admixed with frbm to A; itsvolume of an aqueous solu- UNITED STATES PATENTS tion of 40%tetra-alkylol ammonium hydroxide. N

15. A bath as set forth in claim 14 in which the $333; ag f alkylolderivative is tetra-ethanol ammonium hydroxide. 5 OTHER REFERENCESTHOMAS C. T Synthetic Organic Chemicals, Carbide & Carbon ChemicalsCorp., 11th ed., June 1, 1942, page 61. REFERENCES CITED MatthewsTextile Fibers, 5th ed., John Wiley & The following references are ofrecofd in the Sons, Inc., 1947, page 721. file of this patent: 10 v 7

1. THE PROCESS FOR TREATING CELLULOSE FIBERS WHICH COMPRISESIMPREGNATING SAID FIBERS WITH AN AQUEOUS SOLUTION OF ESSENTIALLY ANALKYLOLAMINECOPPER COMPLEX AND AN AMOUNT OF A TETRA-ALKYLOL AMMONIUMHYDROXIDE TO FORM WITH SAID COMPLEX A SOLENT FOR SILK FIBERS AND INWHICH SOLUTION IS DISSOLVED SILK, WASHING SAID IMPREGNATED FIBERS WITHAN AQUEOUS SOLUTION OF AN ACIDIC AGENT YIELDING WATER-SOLUBLE SALTS WITHSAID COPPER COMPLEX AND WITH SAID TETRA-ALKYLOL AMMONIUM HYDROXIDE, ANDREMOVING SUBSTANTIALLY ALL OF SAID WATERSOLUBLE SALTS FROM SAIDCELLULOSE FIBERS.